A checkout system (register system) of a semi-self-type includes a register that carries out product registration and a payment apparatus (checkout apparatus) that carries out payment processing in a supermarket or the like. In the checkout system, the operation of the register is usually performed by a store clerk, and the operation of the payment apparatus is usually performed by a shopper, respectively.
Also, payment amount for a transaction is transmitted from the register to the payment apparatus for the payment processing, when the payment apparatus is not in use. That is, the register may not be able to carry out product registration for another transaction without transmitting the payment information for the transaction, which may cause delay of the entire checkout process. It is desirable to efficiently perform the entire checkout process.